//创建Person构造函数，参数为name,age

function Person(name,age){

    this.name = name;

    this.age = age;

}

function _new(){

    //1.拿到传入的参数中的第一个参数，即构造函数名Func

    var Func = [].shift.call(arguments);

    //2.创建一个空对象obj,并让其继承Func.prototype

    var obj = Object.create(Func.prototype);

    //3.执行构造函数，并将this指向创建的空对象obj

    Func.apply(obj,arguments)

    //4.返回创建的对象obj

    return obj

}

xm = _new(Person,'xiaoming',18);

console.log(xm);

if (typeof Object.create !== "function") {

    Object.create = function (proto, propertiesObject) {

        if (typeof proto !== 'object' && typeof proto !== 'function') {

            throw new TypeError('Object prototype may only be an Object: ' + proto);

        } else if (proto === null) {

            throw new Error("This browser's implementation of Object.create is a shim and doesn't support 'null' as the first argument.");

        }

        if (typeof propertiesObject != 'undefined') throw new Error("This browser's implementation of Object.create is a shim and doesn't support a second argument.");

        function F() {}

        F.prototype = proto;

        return new F();

    };

}

if (!Function.prototype.bind) {

  Function.prototype.bind = function(oThis) {

    if (typeof this !== 'function') {

      // closest thing possible to the ECMAScript 5

      // internal IsCallable function

      throw new TypeError('Function.prototype.bind - what is trying to be bound is not callable');

    }

    var aArgs   = Array.prototype.slice.call(arguments, 1),

        fToBind = this,

        fNOP    = function() {},

        fBound  = function() {

          // this instanceof fNOP === true时,说明返回的fBound被当做new的构造函数调用

          return fToBind.apply(this instanceof fNOP

                 ? this

                 : oThis,

                 // 获取调用时(fBound)的传参.bind 返回的函数入参往往是这么传递的

                 aArgs.concat(Array.prototype.slice.call(arguments)));

        };

    // 维护原型关系

    if (this.prototype) {

      // Function.prototype doesn't have a prototype property

      fNOP.prototype = this.prototype;

    }

    // 下行的代码使fBound.prototype是fNOP的实例,因此

    // 返回的fBound若作为new的构造函数,new生成的新对象作为this传入fBound,新对象的__proto__就是fNOP的实例

    fBound.prototype = new fNOP();

    return fBound;

  };

}